Independent needle knitting machines

ABSTRACT

The invention is directed to means for reducing the friction load between the butts of the needles and the needle operating cams of independent needle knitting machines and also for reducing the friction load between the needles and the sinkers of such machines and the yarn knitted thereby. Such reduction of frictional loads is achieved by applying high frequency vibrations or oscillations, suitably in the high sonic to the ultrasonic range, to the needle operating cams of the machine by the use of electromechanical transducers positioned in contact with and for transmission of vibrations to the cam boxes or to a ring on which the cam boxes are mounted.

[ Sept. 12, 1972 [S4] INDEPENDENT NEEDLE KNITTING MACHINES [72]Inventor: Jagmohan Singh, Hamburg, Pa.

[73] Assignee: North American Rockwell Corporation, Pittsburgh, Pa.

22 Filed: Nov. 23, 1970 21 Appl.No.: 91,772

Black & Munden, Increasing the Rates of Fabric Production of WeftKnitting Machinery, July 1970, Journal of the Textile Institute, pp. 325348.

Dangel, Cam Action in Weft Knitting, Knitted Outerwear Times Yearbook1968, Vol. 37, No. 19, May 2, 1968, pp. 278- 283.

McMaster, Sonic Power- University Research With An Industrial Payoff,Reprint from July 1967, New in Engineering.

Primary ExaminerWm. Carter Reynolds Attorney-John R. Bronaugh, Floyd S.Levison, E. Dennis OConnor and Richard A. Speer [57] ABSTRACT Theinvention is directed to means for reducing the friction load betweenthe butts of the needles and the needle operating cams of independentneedle knitting machines and also for reducing the friction load betweenthe needles and the sinkers of such machines and the yarn knittedthereby. Such reduction of frictional loads is achieved by applying highfrequency vibrations or oscillations, suitably in the high sonic to theultrasonic range, to the needle operating cams of the machine by the useof electromechanical transducers positioned in contact with and fortransmission of vibrations to the cam boxes or to a ring on which thecam boxes are mounted.

5 Claims, 7 Drawing Figures 1 INDEPENDENT NEEDLE KNITTING MACHINESBACKGROUND OF THE INVENTION The instant invention is directed to thesolution of friction problems encountered in the operation ofindependent needle knitting machines, particularly circular knittingmachines, as for example machines for producing womens tubular hosieryemploying a plurality of knitting stations whereby a correspondingplurality of courses of knitted fabric are produced upon each revolutionof the needle cylinder. Hence the following disclosure will be directedto the application of the invention to such machines. It is to beunderstood however that the use of the invention is not limited tohosiery machines and that it may be equally well applied with attendantadvantages to large diameter multifeed circular body fabric machines andto straight independent needle machines.

In order to increase the production of hosiery machines of the typereferred to above recent developments have been in the direction ofincreasing the number of knitting stations and also of increasing therelative speeds of rotation of the needle cylinder with respect to thecam boxes and other elements defining the knitting stations. Howeverdifficulties have been encountered in such endeavors inasmuch as theincrease in the number of feeds has necessarily required steeper anglesfor the needle manipulating cams in order to accommodate the additionalcam sets around the needle cylinder. For example in an eight-feed womenshosiery machine having a needle cylinder diameter of the order of 4inches the needle raising and stitch drawing cams at each of the feedsmust have angles to the horizontal of approximately 45. It has beenfound that the resulting friction load between the needle butts and thecams has limited the speed of rotation of the needle cylinder incommercial use to from 250 to 300 r.p.m., if undue heating, breakage ofneedle butts and other undesirable effects are to be avoided It has beennoted however that the use of stitch drawing cams with steeper angleshas one salutory effect, namely a reduction in the friction load betweenthe yarn on the one hand and the needle hooks and stitch drawingplatforms of the sinkers on the other. This follows from the fact thatthe steeper the cam angle the fewer the needles and sinkers involvedwith the yarn in the stitch drawing operation resulting in lower yarntension at the stitch point. This advantage has not however outweighedthe disadvantages heretofore inherent in independent needle knittingmachines having steep cam angles.

The principal object of the instant invention is the substantialreduction of the friction load between the needle butts and theiroperating cams while at the same time preserving and enhancing thereduction of the friction load between the yarn and the yarnmanipulating elements, namely the needles and sinkers, presentlyachieved through the employment of relatively steep operating cams.

BRIEF SUMMARY OF THE INVENTION In accordance with the instant inventionthe foregoing object, and other objects as will become apparent, areattained by subjecting the needle operating cams of an independentneedle knitting machine, such as a multifeed circular knitting machine,to rapid vibrations or oscillations of small amplitude the vibrations oroscillations being in the range of 10,000 to 100,000 cycles per second.The rapid vibration or oscillation of the cams, which maintains theneedle butts out of contact with the cams, as the needles travelupwardly of the needle upthrow or raising cam and downwardly of thestitch cam, for a substantial portion of each vibratory cycle, greatlyreduces the friction load between the needle butts and the cams. As aconsequence cams with angles to the horizontal of 45 or greater may besuccessfully employed with the needle cylinder rotating at much higherspeeds than heretofore possible such speeds approximating 600 r.p.m. orhigher. The steeper cam angles permitted by the present invention alsoreduce the number of contacts between the yarn on the one hand and thesinkers and needles on the other and furthermore the vibration of theneedles as caused by the vibrating knitting cams result in a decrease inthe coef ficient of friction between the yarn and such knitting elementsthus decreasing the yarn tension at the stitch point.

The vibrations or oscillations of the several cams making up a cam setat each of the knitting stations are obtained through the employment ofelectromechanical transducers of well known type which transform highfrequency electrical impulses into high frequency mechanical impulsesthe output ends or horns of the transducers being applied directly toeach cam set or to rings supporting the several cam sets. Thetransducers may be of either the piezoelectric or the magnetostrictivetypes capable of producing vibrations or oscillations at frequencies ofthe order of 10,000 to 100,000 cycles per second. In the preferred formof the invention the cam set for the several knitting stations aremounted in boxes fixed to a cam supporting member or plate surroundingthe needle cylinder the cam supporting plate having a plurality of armswhich in turn are supported from the frame of the machine. Thetransducers are supported in vertical positions to have their outputends or horns resting against the arms of the cam supporting plate.

As is well known transducers of the type referred to produce standingwave patterns having locations of maximum velocity and displacement atintervals of one-half wavelength and locations or nodes of minimumvelocity and displacement also at intervals of one-half wavelength thelatter being spaced onequarter wavelength from the former. In theembodiment of the invention the transducers are so located inrelationship to the cam sets and the supports for the cam ring that thecam sets are at the location of maximum velocity and displacement andthe points of support of the cam ring are at the nodes of the wavepattern.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a multifeedknitting machine incorporating the instant invention;

FIG. 2 is a sectional view on an enlarged scale taken on the line 2-2 ofFIG. 1;

FIG. 3 is a sectional view on a further enlarged scale taken on the line3-3 of FIG. 2;

FIG. 4 is a detailed view on an enlarged scale of the upper portion ofFIG. 3;

FIG. 5 is a top plan view similar to FIG. 1 of a circular knittingmachine incorporating a second embodiment of the invention;

FIG. 6 is a top plan view similar to FIG. 1 of a circular knittingmachine incorporating a third embodiment of the invention; and

FIG. 7 is a top plan view similar to FIG. 1 of a circular knittingmachine incorporating a fourth embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawingsand particularly to FIGS. 1 to 3 inclusive there is diagrammaticallyillustrated a circular knitting machine of the type adapted to producewomens hosiery and the like. The machine includes, in addition to otherconventional features many of which are not shown as they are notinvolved in the instant invention, a rotatable needle cylinder 10supporting a circle of individually activated needles 11 mounted inslots in the needle cylinder in the usual manner and each having a butt12 (FIG. 2 and 3). The needle cylinder may be rotated by conventionalmeans indicated by a bevel ring gear 13 on the lower end of the cylinderin mesh with a bevel drive gear 15. The butts of the needles are adaptedto be operated upon at each knitting station by the cams of a cam set 14lying in the path of the needle butts and supported in a cam box 16. Theseveral cam boxes 16, eight of which are shown for an eight-feedmachine, are evenly spaced in fixed positions around the needle cylinderand are mounted on a cam ring 18 which in turn is supported by threeequally spaced cantilever arms 20 secured at one end to the cam ring andat the other end to an annulus 22. Each cam set (FIG. 3) comprises anupthrow cam 24, a stitch cam 26 and a landing cam 28 the several camsbeing secured as by pins or bars 30 to a support block 32, the cam setand block constituting the cam box. The cam box may in addition includepattern controlled means for altering cam positions and the like suchconventional mechanisms not being illustrated herein as they form nopart of the instant invention.

Annulus 22 to which arms 20 are attached includes a downwardly dependingskirt portion 34 having a pair of inwardly directed suitably integrallugs 36 below each arm 20 each pair of lugs being secured as by screwsor studs 38 to one of a plurality of underlying shelf or flange members40 carried by an annular frame member 42. Each member 40 is providedwith a threaded bore 44 receiving a threaded portion of anelectromechanical transducer 46. The displacement amplifier or horn 48of each transducer extends upwardly with its upper end in contact withthe lower side of one of the arms 20. The transducers, which may be ofthe piezoelectric or mangetostrictive type, are of conventionalconstruction and are available from various manufacturers. Each of thetransducers 46 has the capability of transforming high frequencyelectrical impulses into high frequency mechanical impulses orvibrations of the order of l0,000 to 100,000 cycles per second with theamplitude from the micro-inch to the milli-inch ranges at the output endof the horn thereof. In accordance with the instant invention theseveral transducers all have the same frequency and amplitude ofvibration. Each transducer is so located relatively to the length of itsassociated arm 20 and the arms are so dimensioned that the point ofcontact between the transducer horn and an associated arm 20 lies at apoint, at least approximately, one-half of the wavelength induced in thearm by the transducer from the cam set 14 and one-quarter the wavelengthfrom the point of connection of the arm with skirt 34. Hence each camset lies at or adjacent a point of maximum velocity and displacementimparted to the arms 20 by the transducers. The transducers are operatedfrom a suitable electrical source not shown. The energization anddeenergization of the transducers may suitably be under the control ofthe starting switch of the knitting machine or may be separatelycontrolled if desired. In any event on the start of the knittingoperation the transducers are operated and their operation continuingduring preferably the entire knitting cycle.

During the operation of the knitting machine the high frequencyvibrations imparted to arms 20 cause said arms to vibrate the severalcam sets 14. As a result the needles 11 are vibrated or oscillated inplanes normal to their butts as they travel the upward slope of theupthrow cam 24 and the downward slope of stitch cam 26 the butts 12 ofthe needles having only intermittent contact with the cams whereby thefriction load between the needle butts and the cams is substantiallyreduced from the loads heretofore encountered in the operation ofotherwise similar knitting machines. Reduction of the friction loadpermits cams of relatively steep inclines to be employed as for examplecams having angles with respect to the horizontal of 45 or more while atthe same time permitting increased rotational speeds of the needlecylinder relative to the cam sets. Thus relatively steep angled cams asabove mentioned can be employed with the needle cylinder rotating atspeeds up to or approaching 600 rpm. The steep angled cams also by theirnature reduce the friction load between the yarn on the one hand and theneedles and sinkers on the other by limiting the number of needles andsinkers which contact the yarn to a minimum as illustrated in FIG. 3.The latter reduction in friction is further enhanced by the vibratorymotion of the needles with respect to the yarn during the stitch drawingoperation.

DESCRIPTION OF OTHER EMBODIMENTS Referring now to FIG. 5 a secondembodiment of the invention is disclosed. This embodiment, as well asfurther embodiments hereinafter to be described, includes the needlecylinder 10 and the circle of needles 11 as well as other conventionalparts of the knitting machine of the first embodiment. Hence thedescription of the second and further embodiments will be limited to thenovel features residing in the particular mounting of the cam boxes andthe means for application of high frequency vibrations thereof.

In this embodiment the several cam boxes 50, eight of the cam boxesbeing shown, which are equally spaced around the needle cylinder at theknitting stations are individually supported by and secured to the endsof the horns of vertically positioned electromechanical transducers 52.The transducers are of the type previously described for the firstembodiment and all have the same frequency and amplitude of vibration.The transducers are mounted on a ring 54 to which they are affixed. Inoperation the transducers are driven to impart vibrations of the samefrequency and amplitude directly to each of the cam boxes 50.

In the embodiment of FIG. 6 the cam boxes 56, equally spaced around theneedle cylinder at the several knitting stations, are supported by aring 58. Ring 58 is provided with diametrically opposed arms 60 and 62each arm being supported by and secured to a vertically extending post64 affixed to the machine frame. The length of the posts between thering and the machine frame is equal to an odd multiple of the onefourthwavelength. Transducers 66 of the same general type employed in theprevious embodiments are supported to lie in horizontal planes by fixedframe members 68 having threaded openings 70 receiving correspondinglythreaded portions of the transducers. The support of the transducers issuch that the end of the horn 72 of one of the transducers is positionedto lie in contact with one edge of arm 60 and the end of the horn of theother is positioned to lie in contact with the opposite edge of arm 62.The length of the posts 64 between ring 58 and the points of theirsupport by the machine frame is equal to an odd multiple of onefourth ofthe length of the waves induced in the posts by the transducers. Inoperation torsional vibration is imparted to ring 58 whereby the camboxes and the cams supported thereby are subjected to horizontalvibrations but with a similar effect on the butts of the needles asobtained by the other embodiments. Inasmuch as the lengths of posts 64are an odd multiple of a one-quarter wavelength as previously explainedthe lower ends of the posts are in nodal positions.

The embodiment of FIG. 7 which is particularly applicable to four-feedcircular knitting machines includes two pairs of cam boxes 74 one boxbeing provided for each of the four feeds or knitting stations. Each cambox of one pair is carried by and affixed to one of the arms of aright-angled bracket 76. Similarly each cam box of the other pair issupported by one arm of a similar right-angled bracket 78. Each of thearms of the brackets 76 and 78 is secured to and supported by a fixedpost 80 secured to and extending upwardly from the machine frame.Electromechanical transducers 82 of a similar type to those employed inthe other embodiments of the invention are supported from fixed framemembers 84 in positions to have the upper ends of their horns in contactwith the brackets 76 and 78 at their respective elbows. The parts are soproportioned that the spacing between the ends of the transducers incontact with brackets 76 and 78 and posts 80 is approximately equal toone-quarter wavelength of the standing wave imparted to the bracket armsby the transducers. Also the spacing between the transducers and thepoints of securement of the bracket arms to the cam boxes is one-halfsuch wavelength. As a result the cam boxes are located at points ofmaximum velocity and displacement and the supporting posts at points ofminimum velocity and displacement when the transducers are in operation.

In operation the transducers 82 are driven to impart vibrations of thesame frequency and amplitude to both obtainedb the other emb dimen s.

Having thus described my invention in rather complete detail, it will beunderstood that these details need not be strictly adhered to, and thatvarious changes and modifications may be made all falling within thescope of the invention.

I claim:

1. In an independent circular knitting machine having a slotted needlecylinder with a series of butted needles received in the slots and cammeans at a plurality of knitting stations for operating on the butts ofthe needles to cause them to follow needle raising and lowering pathsupon relative movement of the needles past the cam means, theimprovement comprising:

a plurality of electromechanical transducer means to produce highfrequency vibrations,

means mounting said electromechanical transducer means operativelyadjacent the cam means at locations spaced at substantially equaldistances from each other about the needle cylinder, and

means operatively connecting said electromechanical transducer means tothe cam means in a way such that the cam means are subjected to highfrequency vibrations in a plane normal to the needle butts duringrelative movement between the needles and the cam means.

2. A knitting machine as defined in claim 1 wherein said means mountingsaid electromechanical transducer means adjacent the cam means issecured to said knitting machine and is common to all of said transducermeans.

3. A knitting machine as defined in claim 2 wherein said common mountingmeans comprises an annular plate surrounding said machine which platehas arms projecting outwardly therefrom, each said arm having transducermeans associated therewith.

4. In an independent circular knitting machine having a slotted needlecylinder with a series of butted needles received in the slots and camsets at a plurality of knitting stations around the cylinder foroperating on the butts of the needles to cause them to follow needleraising and lowering paths upon relative movement of the needles pastthe cam sets, the improvement comprising:

a plurality of brackets including a pair of arms projecting from acommon point and having free ends to support pairs of the cam sets, thecam sets being mounted adjacent the free ends of said arms, and

an electromechanical transducer individual to each said bracket andmounted in operative contact with each said bracket at each said commonpoint.

5. A knitting machine as defined in claim 4 wherein saidelectromechanical transducers produce standing wave patterns in saidarms and the distance from said common point to the free ends of saidarms is equal approximately to a one-half wavelength of a standard wavepattern.

1. In an independent circular knitting machine having a slotted needlecylinder with a series of butted needles received in the slots and cammeans at a plurality of knitting stations for operating on the butts ofthe needles to cause them to follow needle raising and lowering pathsupon relative movement of the needles past the cam means, theimprovement comprising: a plurality of electromechanical transducermeans to produce high frequency vibrations, means mounting saidelectromechanical transducer means operatively adjacent the cam means atlocations spaced at substantially equal distances from each other aboutthe needle cylinder, and means operatively connecting saidelectromechanical transducer means to the cam means in a way such thatthe cam means are subjected to high frequency vibrations in a planenormal to the needle butts during relative movement between the needlesand the cam means.
 2. A knitting machine as defined in claim 1 whereinsaid means mounting said electromechanical transducer means adjacent thecam means is secured to said knitting machine and is common to all ofsaid transducer means.
 3. A knitting machine as defined in claim 2wherein said common mounting means comprises an annular platesurrounding said machine which plate has arms projecting outwardlytherefrom, each said arm having transducer means associated therewith.4. In an independent circular knitting machine having a slotted needlecylinder with a seRies of butted needles received in the slots and camsets at a plurality of knitting stations around the cylinder foroperating on the butts of the needles to cause them to follow needleraising and lowering paths upon relative movement of the needles pastthe cam sets, the improvement comprising: a plurality of bracketsincluding a pair of arms projecting from a common point and having freeends to support pairs of the cam sets, the cam sets being mountedadjacent the free ends of said arms, and an electromechanical transducerindividual to each said bracket and mounted in operative contact witheach said bracket at each said common point.
 5. A knitting machine asdefined in claim 4 wherein said electromechanical transducers producestanding wave patterns in said arms and the distance from said commonpoint to the free ends of said arms is equal approximately to a one-halfwavelength of a standard wave pattern.